Printed circuit boards are usually mounted in an enclosure and connected to power supplies, panel controls, connectors and other circuitry. In a system where several circuit boards are required, one way to arrange the printed circuit boards is with a cage apparatus. The cage apparatus is generally composed of a rigid assembly with aligned guides to receive individual printed circuit boards, and aligned holes along the rear so that edge connectors can be mounted to mate with the boards. More particularly, the rigid assembly includes two side panels which are separated by several channel members connected along both the top and bottom of the side panels. Conventional card guides made from a dielectric material are connected between the channel members. The standard guides are similar to the guides shown in U.S. Pat. No. 4,019,099, issued to Anthony D. Calabro.
The prior art includes two broad classes of connectors for printed wiring assemblies. In the card edge, or one-part connector, the plug is printed on the end of the printed circuit board as part of the printed wiring. The second class of prior art connector is the two-part connector where the plug portion is formed separately and is mounted as another component on the printed circuit board. Appropriate receptacles are provided for the two types of connector plugs. Thus, the printed circuit board is not energized until its plug end is inserted in the corresponding edge connector or receptacle.
It is often desired to remove the individual printed circuit boards for repair or replacement. However, whether the one or two-part connector is used, problems may occur when the new or repaired board is reinserted into the connector. More specifically, as the printed circuit board is forced into the connector, sharp spikes in the electrical signal directed to the printed circuit board may develop, possibly causing malfunction or damage to the entire electrical system.
At present, in order to avoid the sharp spikes when reinserting a repaired circuit board, prior art cage assemblies are provided with a special zero-insertion force connector to receive either the printed or separate plug of the circuit board. The principal deficiencies of the zero-insertion force connectors are that they are very expensive and time consuming to operate. Alternatively, to prevent the signal spikes, it is always possible to electrically shut down the entire system. However, it is not always practical since this may cause added labor expenses for shut down and start up time, in addition to possible lost production time.
In view of the above, it is an object of the subject invention to provide a cage apparatus for receiving printed circuit boards which permits an electrical potential to be directed across the printed circuit board to preclude spikes in the electrical signal provided to the printed circuit board.
It is another object of the subject invention to provide a cage apparatus for receiving printed circuit boards which can be used to ground the printed circuit boards.
It is a further object of the subject invention to provide a cage apparatus for receiving printed circuit boards which can be used to supply electrical power to the printed circuit boards.
It is another object of the subject invention to provide a cage apparatus for receiving printed circuit boards which can be used to stabilize the voltage potential of the printed circuit boards.
It is an additional object of the subject invention to provide a method for preventing the development of sharp spikes in the signal applied to a printed circuit board inserted in a cage apparatus.